Engine installation using machine vision for alignment

ABSTRACT

Installation of an engine to a support structure includes temporarily attaching first and second alignment structures to the support structure and the engine. One of the alignment structures has a target pattern on its surface. The installation further includes using a machine vision system from the other of the mounting structures to indicate the relative position of the target pattern with respect to a reference. The relative position of the target pattern with respect to the reference provides information about relative position of an engine mounting element (e.g., bolt hole) with respect to a corresponding mounting element (e.g., bolt hole) in the support structure. The relative position of the target pattern with respect to the reference can be used to maneuver the engine in order to align the mounting elements.

BACKGROUND

The Boeing 787 Dreamliner™ airplane has two high bypass turbofanengines, one under each wing. The engines are very large. Each enginehas a length of about 160 inches and a fan diameter of about 110 inches.

The engines are mounted to pylons on the wings. During installation ofan engine, the engine is moved toward a pylon and maneuvered so mountingholes in its mounts are aligned with mounting holes in the pylon. Withthe mounting holes aligned, shear pins are engaged in the engine mounts.Once the shear pins are at full engagement, the engine is moved into itsfinal position and fastened to the pylon with tension bolts.

Maneuvering the engine with respect to the pylon is challenging,especially while lining up the mounting holes for the shear pins.Because the engine is so large and because the mounting holes are at thetop of the engine, visual sight lines to the mounting holes are poor.

SUMMARY

According to an aspect of the present invention, installation of anengine to a support structure includes temporarily attaching first andsecond alignment structures to the support structure and the engine. Oneof the alignment structures has a target pattern on its surface. Theinstallation further includes using a machine vision system from theother of the mounting structures to indicate the relative position ofthe target pattern with respect to a reference. The relative position ofthe target pattern with respect to the reference provides informationabout relative position of an engine mounting element (e.g., a bolthole) with respect to a corresponding mounting element (e.g., a bolthole) of the support structure. The relative position of the targetpattern with respect to the reference can be used to maneuver the enginein order to align the mounting elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a method in accordance with an embodimentof the present invention.

FIG. 2a is an illustration of an aircraft engine mounted to a pylon.

FIG. 2b is an illustration of an aft engine mount.

FIG. 3 is an illustration of apparatus in accordance with an embodimentof the present invention.

FIG. 4 is an illustration of a method of using the apparatus of FIG. 3to install an aircraft engine.

DETAILED DESCRIPTION

Reference is made to FIG. 1, which illustrates a method of aligning amounting hole of an engine with a corresponding mounting hole of asupport structure. By aligning the mounting holes, a pin, bolt or otherfastener can be inserted through the aligned holes so the engine can besecured to the support structure.

At block 110, a first alignment structure (e.g., a plate) is temporarilyattached to the support structure. Components (e.g., a camera) of amachine vision system are already mounted on the first alignmentstructure. The first alignment structure is attached to a known locationon the support structure. This allows the machine vision system toestablish a reference with respect to a known location on the supportstructure.

Also at block 110, a second alignment structure (e.g., a plate) istemporarily attached to the engine. The second alignment structure maybe attached indirectly (e.g., through an engine mount) or directly tothe engine. The second alignment structure has a target pattern on aportion of its surface. This surface portion will hereinafter bereferred to as the “imaging surface.” The target pattern may include oneor more points, lines, shapes, etc. The target pattern may be painted,etched, printed, silk-screened or otherwise placed on the imagingsurface. The target pattern may even be natural feature (e.g., grains)of the imaging surface.

The second alignment structure is attached to a known location on theengine. This places the target pattern at a known location with respectto the engine.

A relative position of the target pattern with respect to the referencecan be observed. This relative position provides information aboutrelative position of an engine mounting hole with respect to acorresponding mounting hole in the support structure (since thelocations of the reference and the target pattern are known on thesupport structure and the engine).

At block 120, the machine vision system is used to indicate relativeposition of the target pattern with respect to the reference. In someembodiments, the machine vision system performs pattern recognition onthe target pattern, acquiring the target pattern and computing distanceand direction of the target pattern from the reference.

In other embodiments, the machine vision system projects the referenceonto the imaging surface of the second alignment structure. For example,the machine vision system projects laser lines onto the imaging surfaceof the second mounting structure. The machine vision system also createsreal-time images of the imaging surface. The images indicate therelative position of the target pattern with respect to the reference(and, therefore, the relative position of the engine mounting hole withrespect to the corresponding mounting hole in the support structure).The machine vision can also process the images to compute distance anddirection of the target pattern from the reference.

At block 130, the information about the relative position of the targetpattern with respect to the reference is used to maneuver the engine inorder to align the mounting holes. For example, the real-time images aredisplayed to those people maneuvering the engine. In addition toproviding the real-time images, the machine vision system can computedistance/direction commands and make such information available to thosepeople maneuvering the engine.

The engine is continually maneuvered until the target pattern coincideswith or overlaps the reference or reaches some other desired positionwith respect to the reference (the target pattern and reference do notnecessarily have to overlap). Once the target pattern and reference arealigned, the mounting holes are aligned, and the engine is in positionto be secured to the support structure.

In some embodiments, the first alignment structure (temporarily attachedto the support structure) may have the imaging surface (including thetarget pattern), and the second alignment structure (temporarilyattached to the engine) may carry the machine vision components.

The alignment structures may be used to align more than one mountinghole at the same time. An example of aligning multiple holessimultaneously is described below.

The mounting holes are not limited to any particular types of holes. Forinstance, the mounting holes may be tension bolt holes, shear pin holes,etc.

Moreover, a method according to an embodiment of the present inventionis not limited to the alignment of mounting holes. Other types ofmounting elements, such as protrusions (e.g., shear pins), may bealigned with corresponding mounting elements.

A method according to an embodiment of the present invention is notlimited to any particular type of engine. However, the method isespecially useful for installing large aircraft engines and other largeengines where sight lines to mounting holes are poor.

Reference is made to FIG. 2a , which illustrates an aircraft engine 210with forward and aft mounts 220 and 230. The forward and aft mounts 220and 230 are attached to a pylon 240, which is beneath a wing 250.

Additional reference is made to FIG. 2b , which illustrates an exemplaryaft mount 230. The aft mount 230 includes shear pin holes 232 andtension bolt holes 234. The aft mount 230 may be attached to the engine210 using spherical-type ball joints, which are designed to allow theengine 210 to move a little during installation.

Reference is made to FIG. 3, which illustrates apparatus 310 foraligning mounting holes of an aircraft engine with mounting holes of apylon 240. In FIG. 3, only the aft mount 230 of the engine is shown. Theengine is not shown for clarity.

The apparatus 310 includes a lower alignment plate 320 having a targetpattern 330 on an imaging surface 325. The apparatus 310 furtherincludes an upper alignment plate 340 that carries two line-projectinglasers 350 and a camera 360. The alignment plates are shaped to avoidinterferences with surrounding structure, yet provide a clear line ofsight from components 350 and 360 to the imaging surface 325.

The upper alignment plate 340 has shallow indexing pins (not shown) thatcan fit into the mounting holes of the pylon 240. The lower alignmentplate 320 has shallow indexing pins (not shown) that can fit into themounting holes of the aft engine mount 230.

The lower alignment plate 320 allows the target pattern to be indexed tothe mounting holes in the engine. By attaching to the engine mountingholes, the exact spatial relation of the target with respect to theengine mounting holes is known.

The upper alignment plate 340 allows a reference line to be indexed tothe mounting holes in the pylon 240. For example, the reference line isformed by a laser line, or by the line of sight of the camera. Byattaching to the pylon mounting holes, the exact spatial relation of thereference line to the pylon mounting holes is known.

The alignment of the reference line with the target pattern 330 can bedetermined on a test/calibration jig, prior to mounting the alignmentplates 320 and 340. The plates 320 and 340 can be aligned on the jig(e.g., by aligning the indexing pins of the two plates 320 and 340), andthe laser lines can be projected on the imaging surface 325 of the lowerplate 320. The target pattern 330 can be placed on the imaging surface325 at the locations where the laser lines fall on the imaging surface325.

If the machine vision system performs the alternative approach ofpattern recognition, the upper alignment plate 340 will carry the camera360, but not the line-projecting laser. Alignment of the target pattern330 and the reference may be determined by aligning the alignment plates320 and 340 on a test/calibration jig, and using the camera 360 to takea picture of the imaging surface plate of the lower alignment plate 320.Pattern recognition software can use that picture as the target pattern.

Additional reference is made to FIG. 4, which illustrates a method ofinstalling an aircraft engine of a wide body aircraft. At block 410, theupper alignment plate is temporarily attached to the pylon by insertingthe shallow indexing pins of the upper alignment plate into tension boltholes of the pylon. The upper alignment plate may be secured to thepylon using slide block hold-down devices.

Also at block 410, the lower alignment plate is temporarily attached tothe engine by inserting the shallow indexing plugs/pins of the loweralignment plate into tension bolt holes of the aft engine mount. Thesealignment plates will allow shear pins to be partially engaged beforethe plates are removed. The lower alignment plate may be secured to theaft engine mount using thumbscrew bolts that extend through the lowerplate.

At block 420, the engine is moved proximate to an alignment position.For example, the engine may be moved approximately one to two feet awayfrom the alignment position.

The engine may be moved, lifted and subsequently maneuvered by atransporter/loader. An exemplary transporter/loader may include anengine engagement unit (e.g., a pair of coupling assemblies) forengaging an engine, a drive assembly (e.g., a multi-directional drivewheel system) for moving the engine to a desired position on a floorsurface, and a lift assembly (e.g., a pair of scissor lift mechanisms)for raising the engine. The engine can be moved and maneuvered withmultiple (e.g., six) degrees of freedom. A single operator can controlthese assemblies from a control station. An exemplary transporter/loaderis described in U.S. Pat. No. 7,103,952. A transporter/loader thatprovides multi-axis positioning of the engine is available from MaxMovelndustrier AB of Bjurholm, Sweden.

However, movement, positioning and maneuvering of the engine is notlimited to a transporter/loader. For instance, overhead cranes, ormobile lifting devices called “Bootstrap Arms” may be used.

At block 430, the camera begins creating real-time images of the imagingsurface. As the engine is being moved toward the alignment position, thelower alignment plate will appear in the images. Then the target patternwill appear.

At block 440, those images are used to provide information about theposition of the target pattern relative to the reference. The images maybe used by displaying them to the operator in real time. Instead of, orin addition, the images may be processed to generate position/directioncommands, which may be displayed to the operator.

At block 450, the operator uses that information to further maneuver theengine into the alignment position. If the operator is viewing real-timeimages, the operator controls the transporter/loader to maneuver theengine so the target pattern approaches the reference. If commands aredisplayed to the operator, the operator controls the transporter/loaderto maneuver the engine according to those commands.

The operator can change the field of view if additional cameras aremounted to the upper alignment plate. The operator can select differentcameras to monitor different aspects of the installation.

At block 460, after the engine has reached its alignment position (e.g.,the target pattern coincides with the reference), the engagement ofshear pins begins. Both alignment plates are removed once shear pinengagement has begun. The tension bolt holes on the engine mount andpylon are now exposed.

At block 470, after the shear pins have been engaged, the engine ismoved to its final mounting position. The engine mount allows for alittle movement of the engine as the transporter/loader moves the engineagainst the pylon. Then the engine is fastened to the pylon with tensionbolts.

At block 480, the forward mount of the engine is also fastened to thepylon. There is no need to use the alignment apparatus on both enginemounts if the mounting holes of the forward engine mount are alreadylined up with corresponding holes in the pylon.

In some embodiments, the engine can be maneuvered into its finalposition hands-free, without the interaction of a human operator. Thecontrol station may include a closed loop control that receivespositional feedback from the machine vision system. In response to thefeedback, the closed loop control commands the transporter/loader tomaneuver the engine. The method of FIG. 4 may be modified for suchclosed loop control. Commands are still generated at block 440, butthose commands are sent to a closed loop control (instead of beingdisplayed to a human operator) at block 450.

A method according to an embodiment of the present invention helps tostreamline the engine installation process. Continual real-timeinformation is available as to the alignment and positioning of anengine relative to a pylon. Installation is faster and allows for moreaccurate relative positioning of an engine with respect to a pylon.

An operator can remotely view the area of engine interface in real timefrom a “desired perspective” (e.g., looking straight down), in an areawhere it is physically impossible for him to see. In addition, theoperator can change the field of view of the camera to focus on the areaof interest during alignment. These images can be viewed from aconvenient location (e.g., at the control station of thetransporter/loader).

A single operator can move an engine into alignment, thereby eliminatingthe need for spotters and, therefore, problems inherent with spotters.Such problems include erroneous communication with the operator (whichcan result in improper positioning of the engine) and injury to thosespotters in the immediate area of the engine-to-pylon interface.

1-11. (canceled)
 12. A method for installing an aircraft engine mount toa pylon, the method comprising: temporarily attaching a first alignmentplate to mounting holes in the pylon, the first plate establishing areference at a known position with respect to the pylon mounting holes;temporarily attaching a second alignment plate to holes in the enginemount, the second plate having an imaging surface with a target pattern,the target pattern having a known position with respect to the enginemount holes; using an imaging device to create images of the imagingsurface; using the images to provide information about the position ofthe target pattern with respect to the reference; using the informationto align shear pin holes in the engine mount and pylon; removing bothplates once shear pin engagement has begun; moving the engine to itsfinal mounting position; and fastening the engine to the pylon.
 13. Themethod of claim 12, wherein an operator uses a transporter loader tomaneuver the engine; and wherein the operator uses the information tocontrol the transporter/loader to maneuver the engine.
 14. The method ofclaim 12, wherein a closed loop, responsive to the information, causes atransporter/loader to maneuver the engine.
 15. Apparatus for installingan engine to a support structure, the apparatus comprising: an enginemount; a first alignment plate for temporarily engaging holes and/orprotrusions of one of the engine mount and the support structure; asecond alignment plate for temporarily engaging holes and/or protrusionsof a second mounting element of the other of the engine mount andsupport structure, the second alignment plate having an imaging surfacewith a target pattern, the target pattern having a known spatialrelationship with the second mounting element; and a machine visionsystem mounted to the first plate, the machine vision system providing areference having a known spatial relationship with the first mountingelement, the machine vision system also creating images of the imagingsurface, the images indicating whether the target pattern is alignedwith a reference.
 16. The apparatus of claim 15, wherein the machinevision system includes a laser system for projecting the reference ontothe imaging surface, the alignment occurring when the target pattern isin a specific position with respect to the projected reference.
 17. Theapparatus of claim 15, wherein the machine vision system stores areference picture of the imaging surface with the target pattern at analignment position, and performs pattern matching to find the referencepicture in the images.
 18. A system comprising: a transporter/loaderincluding a closed loop control for positioning an aircraft engine withrespect to an aircraft support structure; a first alignment plate havinga target pattern on its imaging surface, the first alignment plateengaging the engine at a known location of the engine; a secondalignment plate engaging the support structure; a machine vision systemfor creating images of the imaging surface and determining a relativeposition of the target pattern with respect to a reference; the closedloop control configured to use the relative position to command thetransporter/loader to align mounting elements of the engine and thesupport structure.
 19. (canceled)
 20. (canceled)
 21. The apparatus ofclaim 15, further comprising a transporter/loader for maneuvering theengine to align the holes and/or protrusions of the engine mount withthe holes and/or protrusions of the support structure.
 22. The apparatusof claim 21, further comprising a display for displaying the images to ahuman operator so the human operator can control the transporter/loaderto maneuver the engine.
 23. The apparatus of claim 21, wherein thevision system is configured to determine a relative position of thetarget pattern with respect to the reference.
 24. The apparatus of claim23, wherein the transporter/loader includes a closed loop control forusing the relative position to maneuver the engine to align the holesand/or protrusions of the engine mount with the holes and/or protrusionsof the support structure.
 25. The system of claim 18, wherein themachine vision system includes a laser system for projecting thereference onto the imaging surface, the engine aligned with the supportstructure when the target pattern is in a specific position with respectto the projected reference.
 26. The system of claim 18, wherein thereference is a picture of the imaging surface with the target pattern atan alignment position, and wherein the machine vision system isconfigured to perform pattern matching to match one of the images withthe picture.
 27. The system of claim 18, wherein the first alignmentplate is configured to temporarily engage mounting holes and/orprotrusions in an engine mount of the engine, and the second alignmentplate is configured to temporarily engage mounting holes and/orprotrusions in the support structure, and wherein the mounting elementsare aligned when the mounting holes and/or protrusions of the enginemount are aligned with the mounting holes and/or protrusions of thesupport structure.
 28. The system of claim 27, wherein the mountingelements are aligned when the mounting holes of the engine mount arealigned with the mounting holes of the support structure.
 29. The systemof claim 28, wherein the mounting holes are shear pin holes.